Volvo: Volvo did a jumpstart, now IT wont start., reverse polarity, booster cables

Question
I used my girlfriends 02 Volvo S40 to boost my Chevy truck after I killed the battery by leaving the interior lights on all night. Next day my girlfriend went to start her volvo & clickety click click, wouldnt start, so back to the booster cables, I boosted the volvo & it started fine, I drove it around for about an hour to recharge the battery again & I shut it off, tried to start it again, more clicking. Does this make sense to anyone? I dont see one boost to another car sucking all the life out of a battery, & the Volvo has never ever given problems, Did I somehow fry something?

Answer
If you jumped the batteries incorrectly, you could have done a number of bad things.  The fact that the car drove for an hour after being jumped seems to point to a faulty battery.  Your starter and alternator are fine.  I would start by taking the battery to Pepboys, they'll test it's function for free.  You might discover it no longer takes a charge.  You could have fried it with a reverse polarity hookup.  If the battery checks out, let me know.